From: Kristian Schilling <schilling@nanolytics.de>
  To  : rasmb@alpha.bbri.org
  Date: Thu, 04 Oct 2001 12:16:48 +0200

titanium centerpieces

Hello all,

this is to let you know that double sector titanium centerpieces for the 
XLA/XLI are available from this company.

Some years ago, users in Germany urged Beckman to offer centerpieces made 
of titanium but Beckman was reluctant to take the effort. These users have 
set up a manufacturing of these centerpieces by some companies here in 
Germany and I have taken over the responsibility of distributing them. This 
was the line Beckman encouraged since they are not interested in including 
these parts in their catalogue.

The centerpieces consist of grade 4 titanium, surface roughness is better 
than 1 um. They are resistant to acids, bases and organic solvents. They 
run up to 60 krpm. They fit into standard Beckman housings and alike 
aluminum centerpieces, they require double sector gaskets avilable from 
Beckman Instruments. The optical pathlength is 12 mm.

All cells are tested in our lab; so far, no problems with leakages have 
occurred, though there are some limitations when using very heavy organic 
solvents such as bromoforme above 50 krpm.

The weight is approx. 51 grams. Beckman has stated that they see no 
problems in respect to the increased weight as far as the rotor is 
concerned. If you use quartz windows, you might be able to balance the 
cells with the standard Beckman weight set. With sapphire windows, however, 
this weight set might not be sufficient and it is positively discouraged to 
use extra heavy screws that protude from the weight hole as these screws 
are deformed and might tear off, causing damage to the rotor or the devices 
inside the vacuum chamber. You can estimate from the typical total weights 
of your cells and the weight difference between your current centerpieces 
and titanium whether your counterbalance is heavy enough. If not, we can 
also supply titanium counterbalances that are identical to those from 
Beckman but heavy enough.

So far, only 12 mm centerpieces are available. If there is enough demand 
for 3 mm or six-channel centerpieces, we could attempt to make those 
available as well.

There have been some inquiries recently that I have satisfied by taking 
those centerpieces from our own stock. However, I would like to have 
another series produced before Christmas and must estimate two months for 
the production.
I would be grateful if those of you interested in titanium centerpieces 
could place their requests until the middle of October so I can get this 
going and have a reasonable number manufactured.

The prices for centerpieces and counterbalances are comparable to original 
Beckman parts.

Best wishes,
Kristian


==================================================

          Nanolytics
          Gesellschaft fuer Kolloidanalytik mbH
          Dr.  Kristian Schilling
--------------------------------------------

      Hauptstr. 20
      D-14624 Dallgow

      Tel.:     ++49/3322/24200-5
      Fax:      ++49/3322/24200-6
      e-mail:   schilling@nanolytics.de
      Internet: www.nanolytics.de